Numerical modelling of bottom trawling ground gear element on the seabed

This paper focuses on the numerical modelling of the interaction between gear components, rock- hoppers, in particular and the seabed. This interaction is developed by using the Coupled Eulerian Lagrangian Method (CEL).To demonstrate the rate effect, a 2D finite element model is developed to analyse the pore pressure distribution and soil deformation. In situ soil conditions of the seabed with large deformations require multiphase simulation which is very expensive to investigate numerically. However, fully drained conditions were considered and the results obtained were deemed acceptable for this study. Validation of the numerical model was achieved by means of laboratory experiments undertaken on a 1:5 scaled model. Good agreement between the experimental tests and numerical simulations is found which provides the basis for investigation of the effect of the size of the rockhoppers, their position with respect to the towing direction and the number of discs modelled. A unique expression for the towing force of the segment of rockhopper gear is expressed as a function of the drag force of a single disc, the diameter, thickness, and angle of attack.